Alternative Plasma-Facing-Material Concepts for Extreme Plasma-Burning Nuclear Fusion Environments

One of the most significant design challenges for materials performance exposed to extreme environments (e.g., heat, pressure, and radiation) is maintaining structural integrity while preventing or minimizing long-term damage. In a fusion nuclear reactor the expected operational environment is inherently extreme. The incident plasma will carry heat fluxes of the order of hundreds of MW‧m⁻² and particle fluxes that can average 10²⁴ m⁻²‧s⁻¹ to plasma-facing components (PFCs). The fusion reactor wall will also need to operate at high temperatures near 800 C, and the incident energy of particles will vary from a few electron-volt ions to mega-electron-volt neutrons. The plasma-material interface is a critical region for design since material can be emitted both atomistically (e.g., through evaporation, sputtering, etc.) and/or macroscopically (i.e., during transient events, such as disruptions or edge-localized modes and dust generation) potentially poisoning the fusion plasma. Another challenge is the management of structural damage from neutrons up to hundreds of displacements per atom and transmuted He near 1000 atomic parts per million. Operating duty cycles will demand reliable performance over the course of not just seconds or minutes (i.e., as in most advanced fusion devices today and in the near future) but from months to years. Transformative innovations that can address these significant challenges are opening opportunities in adopting new and novel approaches. Controlling the architecture in advanced materials to tailor properties beyond structure and composition has provided a new paradigm in modern materials design. Tuning properties at localized regions of a cellular material to meet specific functional requirements introduces challenges to modern synthesis and advanced manufacturing methods. Beyond the design of bulk properties in cellular materials is the ability to also design smart, self-healing interfaces. This is particularly important for applications designing advanced materials for future reactor-relevant fusion environments. This paper will give an overview of both the technological gaps and the opportunities from advanced manufacturing that may enable the design of self-healing, adaptive materials for PFCs in future fusion reactor environments. Current progress as well as important innovation challenges will also be discussed.